Metabolic diets with fats are fed and lipoprotein and apolipoprotein levels determined. Marked inter-individual variation in LDL cholesterol responsiveness to dietary changes have been noted. An attempt is being made to correlate diet responsiveness with age, sex, apo E phenotype, ad-lib lipoprotein levels, body mass index and DNA markers. Drug effects on LDL cholesterol levels are being assessed on high and low fat diets.